Screw driver, comprising hyperbolic transition area between tip and shaft in order to prevent high strain acting on shaft

摘要

The screw driver (1) is designed with a tip (2) of any suitable shape and a hexagonal upper shaft (4) for being attached to a power tool or to a grip for manual use. A smooth transitional area (5) in the shape of a hyperbola (7) is located between them (2, 4), transmitting the maximal torque from the shaft (4) to the tip (2) without creating a tension between the two areas.